In recent years, in a digital still camera and/or video camera using a solid-state image pickup element which is a CCD (Charge Coupled Device) type or CMOS (Complementary Metal Oxide Semiconductor) type image sensor, there has been an increasing need for a zoom lens which achieves both compactness, such as a reduction in size and a reduction in thickness, and high performances (large diameter) such as brightness and/or wide angle of view.
On the other hand, as a zoom lens system, there has been conventionally a need for the one with a high optical performance covering from a wide-angle end to a telephoto end, and for example several optical systems answering to the zoom lens of a relatively wide angle are disclosed in Patent Gazette (e.g., see Patent Literatures 1, 2, and 3).
However, in Patent Literature 1, although the focal length is set so as to cover a relatively wide angle with a four-group lens configuration, the F-number is relatively dark, while in Patent Literatures 2 and 3, although the focal length is set so as to cover a relatively wide angle with a five-group lens configuration, the F-number is also dark, and so on, and it is therefore difficult to simultaneously satisfy both an increase in angle of view at a focal length and an increase in brightness.